Web drying



p 1967 J. B. R. CARROLL, JR 3,340,617

WEB DRYING Filed Aug. 18, 1965 FIG.

FIG. 3

INVENTOR. JAMES B. R. CARROLl JR.

ATTORNEY.

fid States Patent 3,340,617 WEB DRYING James B. R. Carroll, Jr.,Philadelphia, Pa., assignor to Selas Corporation of America, acorporation of Pennsylvania Filed Aug. 18, 1965, Ser. No. 480,668 6Claims. (Cl. 34-18) ABSTRACT OF THE DISCLOSURE Fibrous web material isdried by moving it under a high intensity radiant heat source and at thetime time forcing heated air through the web toward the heat source.

The present invention relates to drying, and more particularly to thedrying of continuous strands or webs of fibrous material such as rayontow, for example.

It is necessary to reduce the moisture content of many materials duringtheir manufacture, and this can usually be accomplished by heating them.The application of heat to various materials, however, can reduce theirvalue apprecia bly if it is not done with care. This is particularlytrue in the drying of materials having a high moisture content and arelatively low scorching temperature. Extreme care is required in dryingsuch materials because of the danger of scorching them or in casehardening the surface so that migration of moisture from below thesurface is impaired or stopped.

' It is an object of the invention to provide a method and aparatus forrapidly drying a continuous strand or web of fibrous material.

It is a further object of the invention to dry rapidly fibrous orsimilar material with radiant and convection heat in such a manner thatthe heat is prevented from scorching the material.

In many cases drying has been accomplished by guiding the moist fibrousmaterial over a perforated drum. Heat has then been directed against thematerial moving on the drum to evaporate the moisture. At the same timeair has been drawn through the material into the drums and discharged.This type of operation has the disadvantage that the air between thesource of heat and the material is dry thus permitting the fullintensity of the heat to strike the material. If the material has arelatively low scorching temperature, for example, the heat must beapplied in such a manner that the drying process is relatively slow sothat the material will not be damaged.

In practicing the present invention, the material to be dried is guidedover a perforated surface, and under a source of radiant heat of highintensity directed toward it. Air, which may be heated, is blown throughthe material toward the radiant heat source to drive and carry moisturefrom the material to be evaporated, and also to protect the materialfrom scorching.

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,however, its advantages and specific objects attained with its use,reference should be had to the accompanying drawings and descriptivematter in which I have illustrated and described a preferred embodimentof the invention.

In the drawings:

FIG. 1 is a view partly in section taken on line 1-1 of FIG. 2;

FIG. 2 is a view partly in section taken from right of FIG. 1; and

FIG. 3 shows a modified form of the invention.

Referring to FIGS. 1 and 2 there is shown a web 1 of fibrous material,which can be rayon tow or a fabric, that is to be dried. The material isdirected around a drum 2 by guide rollers 3-. The drum is mounted on ashaft 4 by means of a solid disc 5 and a spider 6, with the shaft beingjournaled for rotation in supports 7. The drum can be rotated by passageof material around it or by means of a suitable drive through a gear 8on the end of shaft 4.

Air, under pressure, is supplied to the interior of drum 2 through ahousing 9 having an intake 11. The end of this housing engages a flange13 on the end of drum 2 and is provided with some suitable seal so thatthe leakage of air around the end of the housing is negligible. Airescapes through perforations 12 that are closely spaced over the surfaceof the drum and passes in a substantially uniform manner through thelayer of material thereon.

Radiant heat is directed against the exterior of the drum and thematerial thereon from a plurality of burners 14 which produce highintensity radiant heat. These burners may be of any suitable type butare preferably of the type shown in Williams et al. Patent No.3,199,570. These burners are provided with a screen 15 on the frontthereof which is heated to incandescence by means of combustion back ofthis screen. This screen directs the heat against the drum. The burnersare made in units with the units being placed end to end as shown bestin FIG. 2 so that they are substantially equal to the length of drum 2.Individual rows of burners are mounted on pipes 16 with the variouspipes being fastened to a substantially circular manifold 17. Thearrangement is such that a plurality of burners are located in rowsaround the periphery of drum 2 with the burners being spaced from 1 /2to 5 inches away from the surface of the drum. There may be provided, ifdesired, a hood 18 over the entire apparatus through which the moisturedriven from the material being dried, can be withdrawn from theenvironment of the apparatus.

In the operation of the apparatus, air, which may be heated to about 200F. is blown outwardly through openings 12 of drum 2 to pass evenlythrough the material thereon. Burners 14 are ignited and the screens 15heated to incandescence, about 1575 F., with the heat being directedtoward the material. The air, being below the wet bulb temperature, willcarry evaporated moisture with it as it leaves the material. Theevaporation of the moisture in the air plus evaporation of theadditional' Water, or other liquid, which is carried or migrates to thesurface of the material will keep the temperature of the material belowthe scorching point. Thus, during the entire drying period the surfaceof the material is moist. This not only protects the surface from theintense heat, it helps to speed up the drying process appreciably. Thematerial may be passed successively over a series of drums if desired,the number depending upon the speed of the material, its originalmoisture content and the desired final moisture content.

Another form which the invention may take is shown in FIG. 3. In thisform, the web of material is supported as it travels'through a path, bymeans of a plurality of rollers 21 and the web is held against thisplurality of rollers by a series of guides 22 which may be stationary oralso may be in the form of rollers.

Between the first pair of rollers and below the web, there is a duct 23that is supplied with air through a pipe 24. The upper surface of theduct, facing the material, is provided with a plurality of openings 25through which air may be forced to flow substantially throughout thearea of the material passing over the duct. In this case, radiant heatis directed against the upper surface of the material from aconventional radiant cup type burner 26 that is supplied with a fuel andair mixture through a pipe 27. Operation of this type of burner is wellknown. It is noted that the duct 23 will extend in a directionperpendicular to the plane of the drawing for a length at least equal tothe width of the web of material being dried, and that the burners willbe placed side by side to form a row of burners at least equal to thewidth of the Web of material.

Between the second and third rollers 21 there is provided a duplicateair duct and burner arrangement except that in this case, the air ductis above the web of material and the air is blown downwardly while theburners are below the web and direct their heat upwardly. In thisfashion moisture is removed alternately from opposite sides of the webas it is moving through the apparatus. Obviously, as many of the ductand burner units as are necessary may be used. In each case, however,they will be reversed so that air will first flow upwardly thendownwardly through the web of material in order to obtain even drying.

The operation of this form of invention is the same as that previouslydescribed as far as the drying and the final product is concerned. Inthe case of some types of fibers, however, more effective and rapiddrying may be obtained by the reversal of the flow of air through thematerial. This feature may also be obtained with the apparatus of FIGS.1 and 2 by suitably locating the drums and guiding the material.

Thus it will be seen that I have provided a method and apparatus bymeans of which a mat or web of fibrous material can be rapidly driedwithout scorching or otherwise harming the material.

While in accordance with the provisions of the statutes I haveillustrated and described the best form of embodiment of my inventionnow known to me, it will be apparent to those skilled in the art thatchanges may be made in the form of the apparatus disclosed withoutdeparting from the spirit and scope of the invention set forth in theappended claims, and that in some cases certain features of my inventionmay be used to advantage without a corresponding use of other features,

What is claimed is:

1. The method of drying at fibrous material which cornprises providing asource of radiant heat at a temperature above that required to evaporatemoisture in the material, moving the material directly through the pathof the radiant heat emanating from said source at a distance from thesource so that the heat is of an intensity normally to damage thematerial, and blowing air through the material toward the source ofheat.

2. The method of drying a fibrous material which comprises forming thematerial into a web, moving the web through a path, providing a sourceof radiant heat at a temperature high enough to evaporate the moisturein the web, directing the radiant heat toward and directly against oneface of the web as it is moving through a portion of said path, andblowing air through the web from the other face thereof toward saidsource of radiant heat as the web moves through said portion of saidpath.

3. The method of drying a fibrous material which comprises continuouslymoving said material in a wet condition over a surface having amultiplicity of openings therein, forcing air through said surface intoand through said material to evaporate moisture therein, directingradiant heat of at least a sufficient temperature to evaporate themoisture directly toward the material carried by said surface toevaporate the moisture in the material directly and withdrawing themoisture laden air.

4. The method of drying fibrous material which comprises moving thematerial to be dried in the form of a web having opposite surfacesthrough a path, at a first location along said path directing radiantheat against one surface of said material, blowing air through saidmaterial at said location from the opposite surface toward the source ofradiant heat, at a second location along said path directing radiantheat against said opposite surface of the material, and at said secondlocation blowing air through said material from said first mentionedsurface toward said opposite surface and said second mentioned source ofradiant heat.

5. Apparatus for drying a web of fibrous material comprising incombination a hollow cylinder having a surface provided with amultiplicity of openings, means to guide a web of fibrous materialaround a portion of said cylinder, means to supply air to the interiorof said cylinder to flow outwardly through said openings and the webpassing around said cylinder, a plurality of burners of a type operativeto produce'radiant heat, and means to mount said burners to direct heatproduced by them directly against the exterior of that portion of saidcylinder around which the web is guided.

6. Apparatus for drying a fibrous material comprising in combination,means forming a path through which the material is moved, a perforatedmember over which the material moves located along said path, means toforce air through the perforations of said member and the material infront thereof, a device for producing radiant heat, and means to mountsaid device at said location on the opposite side of said material fromand directly opposite said perforated member whereby radiant heat willbe directed toward said material in opposition to the air flowing fromsaid member and toward said device.

References Cited UNITED STATES PATENTS 1/1963 Dapses 34-41 KENNETH W.SPRAGUE, Primary Examiner,

1. THE METHOD OF DRYING A FIBROUS MATERIAL WHICH COMPRISES PROVIDING ASOURCE OF RADIANT HEAT AT A TEMPERATURE ABOVE THAT REQUIRED TO EVAPORATEMOISTURE IN THE MATERIAL, MOVING THE MATERIAL DIRECTLY THROUGH THE PATHOF THE RADIANT HEAT EMANATING FROM SAID SOURCE AT A DISTANCE FROM THESOURCE SO THAT THE HEAT IS OF AN INTENSITY NORMALLY TO DAMAGE THEMATERIAL, AND BLOWING AIR THROUGH THE MATERIAL TOWARD THE SOURCE OFHEAT.